U.S. Pat. Nos. 3,480,642, 3,574,845 and 3,682,952 disclose various benzimidazole carbamates, including lower alkyl benzimidazole carbamates, for example, (5-butyl-1H-benzimidazol-2-yl)carbamic acid, methyl ester as possessing anthelmintic properties and useful in the treatment of Syphacia obvelata and Aspicularis tetraptera (mouse pinworm), Nematospiroides dubius, the migratory stages of Ascaris suum, Toxocara canis, Ancylostoma caninum, Trichuris vulgaris, Physaloptera spp, Haemonchus contortus, Ostertagia spp, Trichostrongylus spp, Nematodirus spp, Trichuris ovis, Cooperia spp, Strongyloides papillosus, Bunostomum trigonocephalum and Oesophagostomum spp.
Unfortunately, the compounds described above have been found to have only marginal activity against sheep liver fluke (Fasciola hepatica) and other liver flukes and thus are not recommended for use against such infestations.
Tribromosalan (3,5-dibromo-N-(4-bromophenyl)-2-hydroxybenzamide or 3,4',5-tribromosalicylanilide) originally disclosed in U.S. Pat. Nos. 2,967,885, 3,064,048 and 3,057,920 has been found to be somewhat active in treating Fasciola infections as disclosed in the following papers: J. Hildebrandt, The Veterinary Record, June 15, 1968, pp. 699-700; J. C. Boray et al, The Veterinary Record, Feb. 6, 1965, pp. 175-177; and J. C. Boray et al, The Veterinary Record, Feb. 11, 1967, pp. 218-224.